Method and apparatus for a spacer for an electrode layer gap in a power source

ABSTRACT

The present subject matter includes a capacitor that includes at least a first element having at least a first element thickness, and including a first separator disposed between a first electrode and a second electrode, the first electrode having a first connection member with a first proximal portion and a first foldable portion, the first foldable portion folded onto and abutting the first proximal portion, the abutting first proximal portion and first foldable portion having a first thickness approximately equal to the first element thickness and at least a second element having a third electrode with a second connection member, the first element and the second element stacked in a capacitor stack, wherein the first connection member and the second connection member are in alignment defining a connection surface for connection of the first electrode and the third electrode, with the capacitor stack and electrolyte disposed in a case.

CROSS REFERENCE TO RELATED APPLICATIONS

The following commonly assigned U.S. Patents are related to the presentapplication and are incorporated herein by reference in their entirety:“High-Energy Capacitors for Implantable Defibrillators,” U.S. Pat. No.6,556,863, filed Oct. 2, 1998, issued Apr. 29, 2003; “Flat CapacitorHaving Staked Foils and Edge-Connected Connection Members,” U.S. Pat.No. 6,687,118, filed Nov. 3, 2000, issued Feb. 3, 2004; “Flat Capacitorfor an Implantable Medical Device,” U.S. Pat. No. 6,699,265, filed Nov.3, 2000, issued Mar. 2, 2004. Additionally, the following commonlyassigned Provisional U.S. Patent Application is related to the presentapplication and is incorporated herein by reference in its entirety:“Method and Apparatus for Single High Voltage Aluminum CapacitorDesign,” Ser. No. 60/588,905, filed on Jul. 16, 2004.

TECHNICAL FIELD

This disclosure relates generally to capacitors, and more particularly,to method and apparatus for a spacer for an electrode layer gap in apower source.

BACKGROUND

As technology progresses, the sizes of electrical interconnectionsbecome smaller. Concurrent and related to these size reductions,electronic components are becoming more compact, occupying new, smallershapes. Electronic components of reduced size, having new shapes,require new methods and structures.

One electronic component having electrical interconnections is thecapacitor. To promote size reductions, new shapes, and improvedmanufacturing, new interconnection methods and structures are needed.These new interconnections should not damage capacitors or theirsubcomponents, and should form robust connections.

SUMMARY

The above-mentioned problems and others not expressly discussed hereinare addressed by the present subject matter and will be understood byreading and studying this specification.

One embodiment of the present subject matter includes an apparatus,comprising: at least a first element having at least a first elementthickness, and including a first separator disposed between a firstelectrode and a second electrode, the first electrode having a firstconnection member with a first proximal portion and a first foldableportion, the first foldable portion folded onto and abutting the firstproximal portion, the abutting first proximal portion and first foldableportion having a first thickness approximately equal to the firstelement thickness; and at least a second element having a thirdelectrode with a second connection member, the first element and thesecond element stacked in a capacitor stack, wherein the firstconnection member and the second connection member are in alignmentdefining a connection surface for connection of the first electrode andthe third electrode, with the capacitor stack and electrolyte disposedin a case.

One additional embodiment of the present subject matter includes anapparatus, comprising: at least a first element having a first elementthickness, including at least a first substantially planar electrodewith a first connection member, at least a second substantially planarelectrode, and a first spacer member; and at least a second elementhaving a third substantially planar electrode with a second connectionmember, the first element and the second element stacked in alignmentand defining a capacitor stack, the capacitor stack disposed in a casecontaining electrolyte, wherein the first spacer member, the firstconnection member, and the second connection member are in adjacentalignment defining a connection surface for electrical connection of thefirst substantially planar electrode and the third substantially planarelectrode, with the adjacent first spacer member and first connectionmember having a first thickness approximately equal to the first elementthickness.

Additionally, one embodiment of the present subject matter includes amethod for producing a capacitor stack, comprising: stacking a firstelectrode onto a first element, the first electrode having a firstconnection member having a first proximal portion and a first foldableportion; folding the first foldable portion onto the first proximalportion; stacking the first element onto a second element having atleast one second electrode and a second connection member; aligning thefirst connection member and the second connection member to define aconnection surface for connection of the first electrode and the secondelectrode; connecting the first electrode and the second electrode atthe connection surface; disposing the stacked first element and secondelement in a case; and filling the case with electrolyte.

One embodiment of the present subject matter includes an apparatus forpatient therapy, comprising: a flat capacitor stack having at least afirst separator disposed in alignment between a first substantiallyplanar electrode and a second substantially planar electrode, the firstsubstantially planar electrode having a first connection member with afirst proximal portion and a first foldable portion, the first foldableportion folded onto and abutting the first proximal portion, theabutting first proximal portion and first foldable portion having afirst thickness approximately equal to the first element thickness; anda third substantially planar electrode in stacked alignment with thesecond substantially planar electrode, the third substantially planarelectrode having a second connection member, with the first connectionmember and the second connection member are in alignment defining aconnection surface for connection of the first substantially planarelectrode and the third substantially planar electrode; a case having atleast one feedthrough, the capacitor stack sealably disposed in thecase; programmable electronics connected to the capacitor; and a housingadapted for implantation in the patient, the case and programmableelectronics disposed in the housing, wherein the flat capacitor stackand the case are adapted to deliver to the patient from about 5.3 joulesper cubic centimeter of capacitor stack volume to about 6.3 joules percubic centimeter of capacitor stack volume.

Additionally, one embodiment of the present subject matter includes anelectrode stack, comprising: a first element having at least a firstsubstantially planar electrode and a second substantially planarelectrode in stacked alignment; a second element in stacked alignmentwith the first element, the second element having at least a thirdsubstantially planar electrode and a fourth substantially planarelectrode in stacked alignment; a first connection means forinterconnecting the first substantially planar electrode and the thirdsubstantially planar electrode; and a second connection means forinterconnecting the second substantially planar electrode and the forthsubstantially planar electrode, wherein the first substantially planarelectrode and the third substantially electrode are interconnected, andthe second substantially planar electrode and the fourth substantiallyplanar electrode are interconnected, and the electrode stack is adaptedto deliver from about 7.0 Joules/cubic centimeter of electrode stackvolume, to about 8.5 Joules/cubic centimeter of electrode stack volume.

This Summary is an overview of some of the teachings of the presentapplication and not intended to be an exclusive or exhaustive treatmentof the present subject matter. Further details about the present subjectmatter are found in the detailed description and appended claims. Otheraspects will be apparent to persons skilled in the art upon reading andunderstanding the following detailed description and viewing thedrawings that form a part thereof, each of which are not to be taken ina limiting sense. The scope of the present invention is defined by theappended claims and their legal equivalents.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is an isometric view of a flat capacitor according to oneembodiment of the present subject matter;

FIG. 1B is an isometric view of capacitor electrodes, according to oneembodiment of the present subject matter;

FIG. 2A is a top view of an anode for use in constructing a capacitoraccording to one embodiment of the present subject matter;

FIG. 2B is a top view of a cathode for use in constructing a capacitoraccording to one embodiment of the present subject matter;

FIG. 3A is a top view of an anode for use in constructing a capacitoraccording to one embodiment of the present subject matter;

FIG. 3B is a top view of a cathode for use in constructing a capacitoraccording to one embodiment of the present subject matter;

FIG. 4A is a partial perspective view of a capacitor stack, according toone embodiment of the present subject matter;

FIG. 4B is a partial front view of the capacitor of FIG. 4A;

FIG. 5A is a partial perspective view of a capacitor stack, according toone embodiment of the present subject matter;

FIG. 5B is a partial front view of the capacitor of FIG. 5A;

FIG. 6A is a partial perspective view of a capacitor stack, according toone embodiment of the present subject matter;

FIG. 6B is a partial front view of the capacitor of FIG. 6A;

FIG. 7A is a partial perspective view of a capacitor stack, according toone embodiment of the present subject matter;

FIG. 7B is a partial front view of the capacitor of FIG. 7A;

FIG. 8 is a flowchart depicting a method of interconnecting anodes andcathodes of a capacitor according to one embodiment of the presentsubject matter; and

FIG. 9 illustrates an example process for the anodization of an aluminumelectrolytic capacitor electrode, according to one embodiment of thepresent subject matter.

DETAILED DESCRIPTION

The following detailed description of the present invention refers tosubject matter in the accompanying drawings which show, by way ofillustration, specific aspects and embodiments in which the presentsubject matter may be practiced. These embodiments are described insufficient detail to enable those skilled in the art to practice thepresent subject matter. References to “an”, “one”, or “various”embodiments in this disclosure are not necessarily to the sameembodiment, and such references may contemplate more than oneembodiment. The following detailed description is, therefore, not to betaken in a limiting sense, and the scope is defined only by the appendedclaims, along with the full scope of legal equivalents to which suchclaims are entitled.

In various embodiments, flat capacitors with stacked planar orsubstantially planar electrodes are used to power electronic devices.For example, flat capacitors are used in implantable medical devicessuch as implantable cardioverter defibrillators. Capacitors includeanodes and cathodes, and in various embodiments, the anodes and cathodesare divided into interconnected layers. Additionally, in variousembodiments, capacitor layers are organized into one or more elements.Various examples of an element include at least one anode layer and atleast one cathode layer. A number of elements may be interconnected toform a capacitor stack. Elements are used during capacitor constructionto customize capacitor parameters, such as size, shape, power, andvoltage, in various embodiments. For example, elements of a standardsize, having a standard thickness, can be used to create multiplecapacitors of varying thicknesses. Using a standard element for variouscapacitor configurations simplifies manufacturing.

In various embodiments, the present subject matter includes anodes,cathodes, and separators which are stacked in alignment. Someembodiments include layers with connection members used forinterconnecting to other layers. In various embodiments, a connectionmember extends away from the main body of the capacitor stack, enablinginterconnection among capacitor layers. For example, a number of anodeconnection members extend away from a capacitor stack forinterconnection of multiple capacitor anodes. Connection members areadditionally used for cathodes.

In some examples, several stacked elements including anode connectionmembers may have voids between anode connections members, the voidsdefined by the absence of cathode layers and separator layers. Tointerconnect the anode layers, these anode connection members arepressed together, in various embodiments. In some embodiments, the edgesof all the anode layers abut and form a surface for connection. Such aconnection surface is adapted for a laser weld drawn across the surface,for example. However, the pressing step can break the anode layers. Assuch, these examples would benefit from structures and methods whichfacilitate the formation of a connection surface without breaking theanodes.

The present subject matter includes spacer embodiments and connectionmember embodiments which address these needs. For example, inembodiments where a series of anode connection members have voidsbetween them defined by the absence of cathodes and separators, spacerscan fill the voids. Additionally, special anode connection members canfill the voids. These and other embodiments are within the scope of thepresent subject matter.

FIG. 1A shows a flat capacitor 100 constructed according to oneembodiment of the present subject matter. Although capacitor 100 is aD-shaped capacitor, in various embodiments, the capacitor is anotherdesirable shape, including, but not limited to, rectangular, circular,oval or other symmetrical or asymmetrical shapes. Capacitor 100 includesa case 101 which contains a capacitor stack 102. In one embodiment, case101 is manufactured from a conductive material, such as aluminum. Invarious embodiments, the case is manufactured using a nonconductivematerial, such as a ceramic or a plastic.

Capacitor 100 includes a first terminal 103 and a second terminal 104for connecting capacitor stack 102 to an outside electrical component,such as heart monitor circuitry, including defibrillator, cardioverter,and pacemaker circuitry. In one embodiment, terminal 103 is afeedthrough terminal insulated from case 101, while terminal 104 isdirectly connected to case 101. Terminal 103 comprises an aperture incase 101, in various embodiments. Additionally, terminal 103 comprises aseal 173 in various embodiments. One embodiment of seal 173 includesepoxy. The capacitor incorporates additional connection structures andmethods in additional embodiments. The present subject matter includes,but is not limited to, additional embodiments disclosed on pages 12-13,59-60, 63-82 of related and commonly assigned Provisional U.S. PatentApplication: “Method and Apparatus for Single High Voltage AluminumCapacitor Design,” Ser. No. 60/588,905, filed on Jul. 16, 2004,incorporated herein by reference.

Capacitor stack 102 includes one or more cathodes, one or moreseparators, and one or more anodes. These components are illustratedthrough break line 164 for explanation. Additionally illustrated areanode connection members 175 and cathode connection member 177. Invarious embodiments, the connection members are in alignment such thatmultiple anode subcomponents are in position for interconnection, andmultiple cathode subcomponents are position for interconnection.

Additionally, in some embodiments, capacitor subcomponents are organizedinto capacitor elements 105A, 105B, 105C, . . ., 105N, illustratedthrough break line 166. In various embodiments, stack 102 is formed intwo steps, including a first step of stacking capacitor components intotwo or more elements 105A, 105B, 105C, . . ., 105N, and a second step ofstacking elements into a capacitor stack. Additional embodiments includeforming a capacitor stack in a single step, or three or more steps.

In various embodiments, each cathode is a metallic planar structure.Varying examples include a cathode layer connected to additional cathodelayers using a variety of methods and structures, including welding andadditional connection methods discussed herein. In some embodiments, thecathodes are coupled to conductive case 101, and terminal 104 isattached to case 101, providing a connection between the cathode andoutside circuitry. In some embodiments, the cathode is coupled to afeedthrough conductor extending through a feedthrough hole.

In various embodiments, a separator is positioned, for example, toinsulate each anode from additional components such as a cathode. Theseparator includes one or more sheets of kraft paper impregnated with anelectrolyte, in various embodiments.

In various embodiments, capacitor stack 102 includes one or more anodes.In embodiments comprised of elements, one or more of the anodes ofcapacitor stack 102 are configured into an element. In variousembodiments, these anode subcomponents are foil shaped. In variousembodiments, anodes can include aluminum, tantalum, hafnium, niobium,titanium, zirconium, and combinations of these metals. In oneembodiment, at least portions of a major surface of each anode isroughened and/or etched to increase its effective surface area. Thisincreases the capacitive effect of the anode on a volumetric basis, invarious embodiments. Various embodiments incorporate other compositions.

In various embodiments, each anode is connected to other anodes of thecapacitor, the connected anodes coupled to feedthrough assembly 103 forelectrically connecting the anode to circuitry outside the case. In someembodiments, the anodes are connected to the case and the cathodes arecoupled to a feedthrough assembly. In various embodiments, both theanode and the cathode are connected to components through feedthroughs.

FIG. 11B shows details of one example of capacitor element 105A, whichis representative of capacitor elements 105B-105N. Element 105A includesa cathode 302, a separator 152, and an anode stack 202. In variousembodiments, other numbers and arrangements of anodes, cathodes, andseparators are utilized. Various embodiment of the present subjectmatter include, but are not limited to, configurations disclosed onpages 41-50 of related and commonly assigned copending Provisional U.S.Patent Publication: “Method and Apparatus for Single High VoltageAluminum Capacitor Design,” Ser. No. 60/588,905, filed on Jul. 16, 2004,incorporated herein by reference.

In various embodiments, cathode 302 is a planar structure attached toother cathodes of capacitor stack 102 and to terminal 104. In someembodiments, cathode 302 can include aluminum, tantalum, hafnium,niobium, titanium, zirconium, and combinations of these metals.Additionally, some embodiments include a cathode which has a coating. Insome of these embodiments, the cathode 302 comprises a titanium coatedaluminum substrate.

Some embodiments having a titanium coated cathode material have a highercapacitance per unit area than traditional aluminum electrolyticcapacitor cathodes. Traditional cathodes which are 98% aluminum purityor higher generally have capacitance per unit area of approximately 250uF/cm² for 30 micron thick cathode, with an oxide breakdown voltage inthe 1-3 volt range. However, a cathode as described above results in acapacitance per unit area which, in some embodiments, is as high as 1000uF/cm² or more.

Advantageously, this provides a single cathode which services an anodewithout exceeding the oxide breakdown voltage. When using a traditionalcathode to service several layers (2 or more) of anode, the cathodevoltage may rise as high as 5 or more volts, which is usually greaterthan the breakdown voltage. When this occurs, the aluminum cathodebegins to form oxide by a hydration process which extracts oxygen fromthe water present in the electrolyte. The reaction produces hydrogen asa byproduct which in turn has the effect of creating an internalpressure within the capacitor, in various embodiments. Embodimentshaving internal pressure can demonstrate an undesirable mechanical bulgein the layers of the capacitor stack, or in the case. As such, thetitanium-coated cathode described above serves as a corrective mechanismfor hydrogen generation.

Separator 152 is located between each anode and cathode, in variousembodiments. In various embodiments, separator 152 consists of sheets ofkraft paper. Various embodiments include separator impregnated withelectrolyte. In some embodiments, separator 152 includes a single sheetor three or more sheets. In various embodiments, the electrolyte can beany electrolyte for an electrolytic capacitor, such as anethylene-glycol base combined with polyphosphates, ammonium pentaborate,and/or an adipic acid solute.

In one embodiment, each anode stack 202 is a multi-anode stack includingthree anode foils 202′A, 202′B, and 202′C. In various embodiments, anodestack 202 includes one, two, three or more anode foils having a varietyof anode shapes. Each anode foil has a major surface 151 and an edgeface 150 generally perpendicular to major surface 151. Anodes 202′A,202′B, and 202′C can include aluminum, tantalum, hafnium, niobium,titanium, zirconium, and combinations of these metals, in variousembodiments.

In one embodiment, anodes 202′A-202′C are high formation voltage anodes.In various embodiments, the anodes are medium and/or low formationvariations. In one embodiment, the major surface of each anode202′A-202′C is roughened or etched to increase its microscopic surfacearea. This increases the surface area of the foil with no increase involume. Various embodiments use tunnel-etched, core-etched, and/orperforated-core-etched structures. Various embodiments utilize otherfoil compositions and classes of compositions.

Depending on which process is used to construct the anode, varioussurfaces are coated with a dielectric. For example, in embodiments wherethe anode shapes are punched from a larger sheet, which has previouslybeen coated with dielectric, only the surfaces which have not beensheared in the punching process are coated with dielectric. But if thedielectric is formed after punching, in various embodiments, allsurfaces are coated. In some embodiments, anodes are punched from alarger sheet to minimize handling defects due to handling during themanufacturing process. For example, if a larger sheet is used as astarting material from which a number of anode layers are punched,machines or operators can grasp areas of the starting material which isnot intended to form the final anode. Generally, in embodiments wherethe entire anode is not covered with dielectric, the anode is aged torestore the dielectric.

Various embodiments include a capacitor stack adapted to deliver between7.0 Joules/cubic centimeter and 8.5 Joules/cubic centimeter. Someembodiments are adapted to deliver about 7.7 Joules/cubic centimeter. Insome embodiments, the anode has a capacitance of between approximately0.70 and 0.85 microfarads per square centimeter when charged atapproximately 550 volts. In various embodiments, these ranges areavailable at a voltage of between about 410 volts to about 610 volts.

In various embodiments, the stack is disposed in a case, and linked withother components, a state which affects some of these values. Forexample, in one packaged embodiment, including a case and terminals, theenergy density available ranges from about 5.3 joules per cubiccentimeter of capacitor stack volume to about 6.3 joules per cubiccentimeter of capacitor stack volume. Some embodiments are adapted todeliver about 5.8 joules. In various embodiments, these ranges areavailable at a voltage of between about 410 volts to about 610 volts.

In various embodiments, a first capacitor stack configuration includesnine cathodes, twenty separators, and twenty-eight anodes. A singleseparator may include one, two, or more sheets of a separator material,such as kraft paper. One way to form such a combination would be tostack eight elements including three anode layers and one elementincluding two anode layers. The number of layers, and the number ofelements, is selectable by a capacitor stack design and manufacturingprocess to achieve a desired capacitor power and thickness, in variousembodiments.

In various embodiments, a second capacitor stack configuration includesnineteen cathodes, forty separators, and fifty-eight anodes. One way toform such a combination would be to stack eighteen first elements, witheach first element including three anode layers, one cathode layer, andtwo separators, with a second element having two anode layers, onecathode layer, and with a third element having two separators, and twoanode layers. The number of layers, and the number of elements, isselectable by a capacitor stack design and manufacturing process toachieve a desired capacitor power and thickness, in various embodiments.The configuration offered as an example should not be construed aslimiting, as other configurations are possible depending on packagingand power needs of various applications.

FIG. 2A shows an anode 202 according to one embodiment of the presentsubject matter. Anode 202 is shown before it is assembled into capacitorstack. Anode 202 includes a main body portion 204 having one or moreconnection members 206. In one embodiment, connection member 206includes one or more separate members attached to the anode by welding,staking, or by using another connection method and/or structure. Invarious embodiments, connection member 206 is a protrusion from the mainbody portion 204. Various embodiments define connection member 206 withan excise operation. Various excise operations include punching andlaser-cutting. The present subject matter can include additional exciseoperations. The present subject matter can include shaping operationsadditionally, such as forging.

In various embodiments, portions of connection member 206 are notetched. Etching can cause an anode to become brittle, and unetchedportions can decrease failure from flexing and other types of stressesinduced in processing and use. Unetched portions are defined in a numberof ways. For instance, in one embodiment, a resin mask is put onportions of connection member 206 to keep those masked portions frombecoming etched during the etching process. This provides for unetched,non-porous sections which improve the weldability of anode edges withrespect to each other. Various embodiments include, but are not limitedto, the teachings disclosed on pages 32-34 of related and commonlyassigned Provisional U.S. Patent Application “Method and Apparatus forSingle High Voltage Aluminum Capacitor Design,” Ser. No. 60/588,905,filed on Jul. 16, 2004, incorporated herein by reference.

Connection member 206 includes a proximal section 208 and distal section210. In the embodiment of FIG. 2A, connection member 206 is an L-shapedmember. However, it can have other shapes. In one embodiment, a portionof a distal section 210 is unetched.

In one embodiment, proximal section 208 is connected to main body 204and is defined in part by a pair of cut-out portions 212 and 214 locatedon opposing sides of proximal section 208. Distal section 210 isconnected to a portion of proximal section 208, in various embodiments.In some embodiments, it is integral with proximal section 208. Distalsection 210 is attached as a separate member, in some embodiments. Inone embodiment, distal section 210 is defined in part by a cut-outportion 216 which is located between main body 204 and distal section210, and a cut-out portion 218 which separates distal section 210 frommain body 204. In this embodiment, connection member 206 is locatedwithin the general shape or outline of anode 202. In variousembodiments, connection member 206 extends further from the main body ofanode 202 or connection member 206 is more internal within the main bodyof anode 202.

In some embodiments, each anode in capacitor stack includes a connectionmember such as connection member 206. In various embodiments, one ormore anode foils in a multi-anode stack have a connection member 206while the other anode foils in the multi-anode stack are connected tothe anode having the connection member. For instance, in one embodiment,a three-foil anode stack includes one foil having a connection member206 and two foils without connection members. The two foils withoutconnection members are welded, staked, or otherwise attached to the foilhaving the connection member.

FIG. 2B shows a cathode 302 according to one embodiment of the presentsubject matter. Cathode 302 is shown before it is assembled into acapacitor stack. Cathode 302 includes a main body portion 304 having oneor more connection members 306. In one embodiment, connection member 306is an integral portion of cathode 302, and is punched, laser-cut, orotherwise shaped from the cathode. In one embodiment, connection member306 includes one or more separate members attached to the cathode bywelding, staking, or other connection method. The present subject matterincludes, but is not limited to, additional embodiments illustrated onpages 13-29 of related and commonly assigned copending Provisional U.S.Patent Application: “Method and Apparatus for Single High VoltageAluminum Capacitor Design,” Ser. No. 60/588,905, filed on Jul. 16, 2004,incorporated herein by reference.

In one embodiment, connection member 306 includes a proximal section 308and a distal section 310. In the embodiment of FIG. 2B, connectionmember 306 is an L-shaped member. However, additional embodiments haveother shapes. In various embodiments, proximal section 308 is connectedto main body 304 and is defined in part by a pair of cut-out portions312 and 314 located on opposing sides of proximal section 308. Distalsection 310 is connected to a portion of proximal section 308. In oneembodiment, it is integral with proximal section 308. In someembodiments, distal section 310 is attached as a separate member. In oneembodiment, distal section 310 is defined in part by a cut-out portion316 which is located between main body 304 and distal section 310, and acut-out portion 318 which separates distal section 310 from main body304. In this embodiment, connection member 306 is located within thegeneral shape or outline of cathode 302. In various embodiments,connection member 306 extends further from the main body of cathode 302or connection member 306 is more internal within the main body ofcathode 302.

For instance, in various embodiments, connection members 206 and 306 maybe in different positions along the edges or even within the main bodyportions of the capacitor foils 202 and 302. For instance, in someembodiments connection members 206 and 306 are located along edges 220and 320 of the respective electrodes 202 and 302. In some embodiments,the portions are located along curved edges 222 and 322 of therespective electrodes 202 and 302. In various embodiments, the portionsmay be cut-out within main bodies 204 and 304. In one embodiment,proximal section 308 of cathode 302 and proximal section 208 of anode202 are located in different positions (relative to each other) on theirrespective electrodes, while distal sections 210 and 310 overlap.

FIGS. 3A and 3B show an anode 202′ and a cathode 302′ according to oneembodiment of the present subject matter. Anode 202′ and cathode 302′are shown before being assembled into capacitor stack. In variousembodiments, anode connection member 206′ does not include a cut-outsuch as cut-out 212 of anode 202. Additionally, in various embodiments,connection member 306′ does not include a cut-out such as cut-out 318 ofcathode 302.

FIG. 4A is a partial perspective view of a capacitor stack, according toone embodiment of the present subject matter. In various embodiments,the capacitor stack includes cathodes 420A, 420B, . . ., 420N,separators 152A, 152B, . . ., 152(N-1), 152N, and anodes 202′A, 202′B, .. ., 202′N.

The anodes 202′A, 202′B, . . ., 202′N include a folded connection member206′A, 206′B, . . ., 206′N. In some embodiments, the folded connectionmember is not etched. Various embodiments include, but are not limitedto, the teachings disclosed on pages 115-119 of related and commonlyassigned Provisional U.S. Patent Publication: “Method and Apparatus forSingle High Voltage Aluminum Capacitor Design,” Ser. No. 60/588,905,filed on Jul. 16, 2004, incorporated herein by reference.

In various embodiments, the folded connection members define aconnection surface 450. In some embodiments, the connection surface iscomprised of edge surfaces of multiple anodes 202′A, 202′B, . . .,202′N. In additional embodiments, other subcomponents contribute to theshape of the connection surface 450.

In various embodiments, the anode component of the element can includefoil subcomponents which do not include a folded connection member. Invarious embodiments, the anode subcomponents are interconnected throughtheir abutting position in a capacitor element. In additionalembodiments, anode foils are interconnected using other forms ofconnection, such as edge welds or solid-state welds such as stake-welds.

FIG. 4B is a partial front view of the capacitor of FIG. 4A. In variousembodiments, a capacitor stack is configured into elements 404A, 404B, .. ., 404N. Element 404A has an element thickness T41, in variousembodiments. Although the illustrated elements 404A, 404B, . . ., 404Ninclude a single anode 202′A, 202′B, . . ., 202′N which is of athickness approximately equivalent to the combined thickness of a stackincluding two separators 152A, 152B, . . ., 152(N-1), 152N and a cathode420A, 420B, . . ., 420N, other embodiments are within the scope of thepresent subject matter. For example, the anode 202′A, 202′B, . . .,202′N can be comprised of several abutting anode foil subcomponentswhich are not pictured.

In various embodiments, the stackable nature of the elements, and thedefinition of a connection surface with only anode connection members,is enabled by selecting anodes, cathodes, and separators of a commonthickness. For example, in various embodiments, folded connection memberhas a thickness T42. In various embodiments, thickness T41 is equivalentto thickness T42.

In various embodiments, the cathode of the illustration ranges fromabout 0.001 inches to about 0.003 inches in thickness. The separatorlayer, in various embodiments, ranges form about 0.00025 inches to about0.001 inches in thickness. Also, the anode ranges from about 0.003inches, to about 0.005 inches in thickness, in varying embodiments. Insome embodiments the anode is comprised of multiple abutting anodefoils. In some of these embodiments, each anode foil is from about0.0035 inches to 0.004 inches thick. The combination of three anodes,for example, ranges from 0.0105 inches to about 0.012 inches. Varyingcapacitor elements can include two or more abutting anode foils as well.

FIGS. 5A-5B present partial views of a capacitor stack, according to oneembodiment of the present subject matter/is a front view of a capacitorstack. FIG. 5B is a perspective view of the capacitor stack. In variousembodiments, the capacitor stack includes cathodes 302′A, . . ., 302′N,separators 152A, 152B, . . ., 152(N−1), 152N, and anodes 202A, 202B, . .., 202(N−1), 202N. In various embodiment, the anodes 202A, 202B, . . .,202(N−1), 202N include folded connection members 206′A, 206′B, . . .,206′N, respectively, which define one connection surface 550.

Additionally shown are first elements 504A, . . ., 504N, and secondelements 505A, . . ., 505N. Although the illustrated first element 504A,. . ., 504N include a single anode 202A, 202B, . . ., 202(N−1), 202Nwhich is of a thickness approximately equivalent to a separator 152A,152B, . . ., 152(N−1), 152N, other embodiments are within the scope ofthe present subject matter. For example, the anode 202A, 202B, . . .,202(N−1), 202N can be comprised of several abutting anode foilsubcomponents which are not pictured. The anode 202A, 202B, . . .,202(N−1), 202N can include one foil which includes a folded connectionmember 206′A, 206′B, . . ., 206′N, in addition to foils which do notinclude a connection member. In these embodiments, the anode foils areinterconnected through their abutting position in a capacitor element.In various embodiments, anode foils are interconnected using other formsof connection, such as edge welds or solid-state welds such asstake-welds.

In various embodiments, the cathode of the illustration ranges fromabout 0.001 inches to about 0.003 inches in thickness. The separatorlayer, in various embodiments, ranges form about 0.0025 inches to about0.002 inches in thickness. Also, the anode ranges from about 0.002inches, to about 0.005 inches in thickness, in varying embodiments. Invarious embodiments the anode is comprised of multiple abutting anodefoils. For example, in one embodiment, each anode foil is from about0.003 inches to 0.005 inches thick. Varying capacitor elements caninclude two or more abutting anode foils.

The cathode 302′A, . . ., 302′N illustrated is useful for filling gapsbetween anode connection members in the construction of an anodeconnection surface, in various embodiments. The cathode 302′A, . . .,302′N as illustrated is cut away, at cut line 552, from the cathodelayers of the main capacitor stack during manufacturing processes.Therefore, in various use embodiments, the cathode 302′A, . . ., 302′Nis not electrically connected to the cathode of the main capacitorstack. The present subject matter includes, but is not limited to, theteachings disclosed on pages 96-100 of related and commonly assignedProvisional U.S. Patent Publication: “Method and Apparatus for SingleHigh Voltage Aluminum Capacitor Design,” Ser. No. 60/588,905, filed onJul. 16, 2004, incorporated herein by reference.

The examples illustrated in FIGS. 4A-5B are not to be understood aslimiting. Various additional embodiments include anode connectionsurfaces with non-folded anode connection members, and folded cathodeconnection members. Additional embodiments include cathode connectionsurfaces having folded anode connection members and/or folded cathodeconnection members. The configurations provided are embodiments whichare useful for explanation, but are not exhaustive or exclusive ofexamples within the scope of the present subject matter.

FIG. 6A is a partial perspective view of a capacitor stack, according toone embodiment of the present subject matter. In various embodiments,the capacitor stack includes cathodes 608A, 608B, . . ., 608N, spacermembers 604A, 604B, . . . 604N, and anodes 606A, 606B, . . . .,606(N−1), 606N. Various embodiments additionally include a connectionsurface 650. Anode 606A, 606B, . . ., 606(N−1), 606N can be comprised ofseveral abutting anode foils which are not pictured, in variousembodiments. Additionally, in various embodiments, separator layers arepositioned behind spacer members 604A, 604B, . . ., 604N, and out ofview. These layers are pictured in perspective view FIG. 6B. As such,the spacer members 604A, 604B, . . ., 604N are approximately as thick asseparator layers.

In some embodiments, spacer members 604A, 604B, . . ., 604N are separatedetached components. In additional embodiments, the spacer members 604A,604B, . . ., 604N are attached to a main spacer body 602. A main spacerbody 602, in various embodiments, is adapted for positioning severalspacer members 604A, 604B, . . ., 604N at once. A main spacer body 602and spacer members 604A, 604B, . . ., 604N can be formed from a unitarymaterial structure. For example, the main spacer body 602 and spacermembers 604A, 604B, . . ., 604N can be made from plastic. Additionalmaterials are also within the scope of the present subject matter. Forexample, a main spacer body 602 and spacer members 604A, 604B, . . .,604N may be machined from aluminum. Further embodiments may be extrudedfrom aluminum.

Additionally shown are first elements 605A, . . ., 605N, and secondelements 607A, . . ., 607N. Although the illustrated first element 605A,. . ., 605N include a single anode 606A, 606B, . . ., 606(N−1), 606Nwhich is of a thickness approximately equivalent to a separator 152A,152B, . . ., 152(N−1), 152N, other embodiments are within the scope ofthe present subject matter. For example, the anode 606A, 606B, . . .,606(N−1), 606N can be comprised of several abutting anode foilsubcomponents which are not pictured. The anode 606A, 606B, . . .,606(N−1), 606N can include one foil which includes a folded connectionmember 610A, 610B, . . ., 610N, in addition to foils which do notinclude a connection member. In these embodiments, the anode foils areinterconnected through their abutting position in a capacitor element.In various embodiments, anode foils are interconnected using other formsof connection, such as edge welds or solid-state welds such asstake-welds.

In various embodiments, the cathode of the illustration ranges fromabout 0.001 inches to about 0.003 inches. The spacer members 604A, 604B,. . ., 604N layer, in various embodiments, range form about 0.001 inchesto about 0.005 inches. Also, the anode ranges from about 0.002 inches,to about 0.005 inches, in various embodiments. In some embodiments theanode is comprised of multiple abutting anode foils. For example, in oneembodiment, each anode foil is from about 0.0035 inches to 0.004 inches.Varying capacitor elements can include two or more abutting anode foils.

FIG. 6B is a partial front view of a capacitor stack with spacers,according to one embodiment of the present subject matter. In variousembodiments, the illustration includes spacer members 604′A, 604′B, . .., 604′N, which are not interconnected. Additionally, illustrated arefirst elements 605A, . . ., 605N, and second elements 607A, . . ., 607N.Although the illustrated first elements 605A, . . . 605N include asingle anode 606A, 606B, . . ., 606(N−1), 606N respectively, which is ofa thickness approximately equivalent to a separator 152A, 152B, . . .,152(N−1), 152N (not pictured), other embodiments are within the scope ofthe present subject matter.

In various examples, the anodes 606A, 606B, . . ., 606(N−1), 606N can becomprised of several abutting anode foil subcomponents. The anodes 606A,606B, . . ., 606(N−1), 606N can include one foil which includes aconnection member, in addition to foils which do not include aconnection member. In various embodiments, the anode foils areinterconnected through their abutting position in a capacitor element.In additional embodiments, anode foils are interconnected using otherforms of connection, such as edge welds or solid-state welds such asstake-welds.

In some embodiments, the connection member is not etched, while theremaining anode is. Various embodiments include, but are not limited to,the teachings disclosed on pages 115-119 of related and commonlyassigned Provisional U.S. Patent Publication: “Method and Apparatus forSingle High Voltage Aluminum Capacitor Design,” Ser. No. 60/588,905,filed on Jul. 16, 2004, incorporated herein by reference.

FIG. 7A is a partial perspective view of a capacitor stack, according toone embodiment of the present subject matter. In various embodiments,the capacitor stack includes cathodes 708A, 708B, . . ., 708N,separators 152A, 152B, . . ., 152(N−1), 152N, spacer members 704A, 704B,. . ., 704N, and anodes 706A, 706B, . . ., 706N. Anodes 706A, 706B, . .., 706N can be comprised of several abutting anode foils which are notpictured, in various embodiments. The illustrated spacer members 704A,704B, . . ., 704N are approximately equivalent in thickness to thecombined thickness of a stack including two separators 152A, 152B, . .., 152(N−1), 152N and a cathode 708A, 708B, . . ., 708N, in variousembodiments.

In some embodiments, spacer members 704A, 704B, . . ., 704N are separatedetached components. In additional embodiments, including theembodiments pictured, the spacer members 704A, 704B, . . ., 704N areattached to a main spacer body 702. A main spacer body 702, in variousembodiments, is adapted for positioning several spacer members 704A,704B, . . ., 704N at once. A main spacer body 702 and spacer members704A, 704B, . . ., 704N can be formed from a unitary material structure.For example, the main spacer body 702 and spacer members 704A, 704B, . .., 704N can be made from plastic. Additional materials are also withinthe scope of the present subject matter. For example, a main spacer body702 and spacer members 704A, 704B, . . ., 704N may be machined fromaluminum.

In various embodiments, the cathode of the illustration ranges fromabout 0.001 inches to about 0.003 inches. The separator layer, invarious embodiments, ranges form about 0.001 inches to about 0.005inches. The spacer members 704A, 704B, . . ., 704N layer, in variousembodiments, range form about 0.002 inches to about 0.005 inches. Also,the anode ranges from about 0.003 inches, to about 0.005 inches, invarying embodiments. In some embodiments the anode is comprised ofmultiple abutting anode foils. For example, in one embodiment, eachanode foil is from about 0.003 inches to 0.005 inches. Varying capacitorelements can include two or more abutting anode foils.

FIG. 7B is a partial front view of a capacitor stack, according to oneembodiment of the present subject matter. In various embodiments, theillustration includes spacer members 704′A, 704′B, . . ., 704′N whichare attached to a main spacer body 702. Examples of such spacer includealuminum ribbons connected to anodes 706A, 706B, . . ., 706N. Aconnection of a spacer members 704′A, 704′B, . . ., 704′N to anodes706A, 706B, . . ., 706N can include stake welding, or other connectionmethods.

Additionally, FIG. 7B illustrates elements 710A, . . ., 710N. Althoughthe illustrated elements 710A, 710B, . . ., 710N include a single anode706A, 706B, . . ., 706N which is of a thickness approximately equivalentto the combined thickness of a stack including two separators 152A,152B, . . ., 152(N−1), 152N and a cathode 708A, 708B, . . ., 708N, otherembodiments are within the scope of the present subject matter. Forexample, the anode 706A, 706B, . . ., 706N can be comprised of severalabutting anode foil subcomponents which are not pictured. In variousembodiments, the anode 706A, 706B, . . ., 706N can include one foilwhich includes a connection member, in addition to foils which do notinclude a connection member. In some of these examples, the anode foilsare interconnected through their abutting position in a capacitorelement. In various embodiments, anode foils are interconnected usingother forms of connection, such as edge welds or solid-state welds suchas stake-welds.

In some embodiments, the connection member is not etched, while thenon-connection member portions of the anode are. Various embodimentsinclude, but are not limited to, the teachings disclosed on pages115-119 of related and commonly assigned Provisional U.S. PatentPublication: “Method and Apparatus for Single High Voltage AluminumCapacitor Design,” Ser. No. 60/588,905, filed on Jul. 16, 2004,incorporated herein by reference.

FIG. 8 shows a flowchart depicting a method 800 for interconnecting twoor more foils of a capacitor according to one embodiment of the presentsubject matter. Method 800 includes a block 802, positioning theconnection members of two or more foils, a block 804, connecting theconnection members, and block 806, electrically isolating portions ofthe connection members from each other.

In one embodiment, block 802 includes positioning the connection membersof two or more foils, includes stacking an anode foil having aconnection member having a proximal section and a distal section upon acathode foil having a connection member having a proximal section and adistal section. The foils and connection members are positioned so thatthe proximal section of the anode foil connection member does notoverlap the proximal section of the cathode foil connection member. Insome embodiments, the distal section of the anode foil connection memberat least partially overlaps the distal section of the cathode foilconnection member.

In one embodiment, block 804 includes connecting the connection membersof an anode to the connection members of a cathode. In variousembodiments, this includes connecting the distal section of the anodeconnection member and the distal section of the cathode connectionmember at a portion of the anode connection member that overlaps theportion of the cathode connection member. In various embodiments,connecting comprises a single, continuous connection process. Variousconnection processes may be used, including laser welding, staking, edgewelding, soldering, swaging, and/or applying an electrically conductiveadhesive. Combinations of these processes are possible as well.

In one embodiment, block 806 includes electrically isolating portions ofthe connection members from each other. In various embodiments, thisincludes removing portions of the anode connection member and portionsof the cathode connection member. In one embodiment, the removed portionincludes an area where the cathode connection member overlaps a portionof the anode connection member. In one embodiment, this includesremoving a portion of the distal sections of the anode connection memberand a portion of the distal section of the cathode connection member. Inone embodiment, electrically isolating comprises punching-out a portionof the distal section of the anode foil connection member and the distalsection of the cathode connection member. In one embodiment,electrically isolating includes laser cutting a portion of the distalsection of the anode connection member and a portion of the distalsection of the cathode connection member.

After being processed as discussed in block 806, proximal sections ofthe connection members of anodes are still coupled to distal sections ofthe cathodes, and proximal sections of the cathode connection membersare still connected to distal portion of the anode, while anodes andcathodes are electrically isolated from each other. Feedthroughs orother terminal members are used to couple the anodes and cathodes tooutside circuitry. Although these examples are useful for demonstratingvarious aspects of the present subject matter, additional examples fallwithin this scope.

FIG. 9 illustrates an example process for the anodization of aluminumelectrolytic capacitor foil, according to the present subject matter. Invarying embodiments, the present subject matter is capable of producinganodized aluminum electrolytic capacitor foil at a formation voltagefrom about 200 volts to about 760 volts, which can result in a capacitorwith a working voltage from about 150 volts to about 570 volts. Forexample, the present subject matter encompasses aluminum oxide formed atbetween approximately 600 volts and approximately 760 volts.Additionally, the present subject matter encompasses embodiments whereanodization occurs from about 653 volts to about 720 volts.Additionally, the present subject matter encompasses embodiments whereinanodization occurs from about 667 volts to about 707 volts duringformation.

Varied processes can be utilized to produce the aluminum foil of thepresent subject matter. For example, one process includes forming ahydrous oxide layer on an aluminum foil by immersing the foil in boilingdeionized water 952. The aluminum foil is also subjected toelectrochemical anodization in a bath containing an anodizingelectrolyte 954 composed of an aqueous solution of boric acid, aphosphate, and a reagent. Additionally, the anodizing electrolytecontains a phosphate. In various embodiments, the anodizing electrolyteis at a pH of approximately 4.0 to approximately 6.0. In some examples,the foil is passed through a bath containing a borax solution 956.Borax, in various embodiments, includes a hydrated sodium borate,Na₂B₄O₇.10H₂O, and is an ore of boron.

In varying embodiments, the foil is reanodized in the boricacid-phosphate electrolyte previously discussed 958. In variousembodiments of the present subject matter, the process produces astabilized foil suitable for oxide formation of up to approximately 760volts.

In various embodiments, the anodizing electrolyte used in block 954 and956 contains about 10 grams per liter to about 120 grams per liter ofboric acid and approximately 2 to approximately 50 parts per millionphosphate, preferably as phosphoric acid, and sufficient alkalinereagent to lower the resistivity to within approximately 1500 ohm-cm toapproximately 3600 ohm-cm and increase the pH from about 4.0 to about6.0 for best anodization efficiency and foil quality.

In some embodiments, the borax bath contains 0.001 to 0.05 moles/literof borax. Because the anodizing electrolyte is acidic, in variousembodiments, the borax bath is buffered with sodium carbonate to preventlowering of the pH by dragout of the acidic electrolyte. Additionally,in various embodiments, the borax bath is buffered to lower itsresistivity. In one example, the pH of the bath is from about 8.5 toabout 9.5, and the temperature is at least approximately 80 degreesCelsius. In varying embodiments, the sodium concentration isapproximately 0.005 to approximately 0.05M, preferably about 0.02 M. Itshould be noted that concentrations of less than approximately 0.005Mare too dilute to control properly, and concentrations aboveapproximately 0.05M increase the pH, resulting in a more reactivesolution which degrades barrier layer oxide quality.

In varying embodiments of the present subject matter, the presence of atleast approximately 2 parts per million phosphate in the acidicanodizing electrolyte is critical. For example, this presence initiatesstabilization of the foil so that solely hydrous oxide dissolves in thealkaline borax bath, without damage to the barrier layer dielectricoxide. In varying embodiments, this lowers ESR (equivalent seriesresistance) of the anodized foil.

Additionally, in various embodiments, when the foil is reanodizedfollowing the alkaline borax bath, the foil surface is alkaline andreacts electrochemically with the phosphate, which, in variousembodiments, results in the incorporation of phosphate into thedielectric oxide. In varying examples, the alkaline foil surfaceincludes an alkaline metal aluminate, and in one embodiment includes asodium aluminate. It should be noted that the amount of allowablephosphate in the anodizing electrolyte, in various embodiments, isinversely proportional to the voltage at which the foil is beinganodized. For example, in one embodiment, using greater thanapproximately 24 parts per million results in failure during oxideformation at around 650 volts. In embodiments where approximately 50parts per million of phosphate is exceeded, the electrolyte scintillatesat the foil interface, resulting in damaged, unstable foil. One benefitof the present subject matter is that an electrode is produced which cantolerate a high formation voltage without scintillation at the boundarylayer of the foil. It should be noted that anodization temperatureshould be maintained from about 85 degrees Celsius to about 95 degreesCelsius, as variance outside of these values results in a the barrierlayer oxide of lower quality, and foil corrosion.

Various aspects of the present subject matter include performanceproperties which enable the capacitor to function as a single capacitorin an implantable medical device 960. In one embodiment, an implantablemedical device is a cardioverter defibrillator. For example, byconstructing the capacitor stack with the methods and apparatuscontained in these teachings, one may construct a capacitor which issuited for use as the sole capacitor used for powering therapeuticpulses in an implantable cardioverter defibrillator. By using a singlecapacitor, instead of two capacitors which are connected in series, thepresent subject matter contributes to weight and size reductions.

Although specific embodiments have been illustrated and describedherein, it will be appreciated by those of ordinary skill in the artthat any arrangement which is calculated to achieve the same purpose maybe substituted for the specific embodiment shown. This application isintended to cover adaptations or variations of the present subjectmatter. It is to be understood that the above description is intended tobe illustrative, and not restrictive. Combinations of the aboveembodiments, and various embodiments, will be apparent to those of skillin the art upon reviewing the above description. The scope of thepresent subject matter should be determined with reference to theappended claims, along with the full scope of equivalents to which suchclaims are entitled.

1. An apparatus, comprising: at least a first element having at least afirst element thickness, and including a first separator disposedbetween a first electrode and a second electrode, the first electrodehaving a first connection member with a first proximal portion and afirst foldable portion, the first foldable portion folded onto andabutting the first proximal portion, the abutting first proximal portionand first foldable portion having a first thickness approximately equalto the first element thickness; and at least a second element having athird electrode with a second connection member, the first element andthe second element stacked in a capacitor stack, wherein the firstconnection member and the second connection member are in alignmentdefining a connection surface for connection of the first electrode andthe third electrode, with the capacitor stack and electrolyte disposedin a case.
 2. The apparatus of claim 1, wherein the first elementthickness is from about 0.0065 inches to about 0.015 inches.
 3. Thecapacitor stack of claim 2, wherein the first electrode is an anode witha thickness of between about 0.003 inches and about 0.005 inches.
 4. Theapparatus of claim 1, wherein the first element includes four layersorganized serially in the order of a second separator, a cathode, thefirst separator, and an anode; and the first separator, cathode, andsecond separator have a combined thickness approximately equal to thethickness of the anode.
 5. The apparatus of claim 1, further comprising:a plurality of layers defining the first element, the first elementhaving the plurality of layers organized serially in the order of afirst anode layer including the first connection member, the firstseparator layer, and a cathode layer having a first cathode connectionmember; and the second element having a plurality of layers including asecond separator and a second anode layer including the secondconnection member; wherein the connection surface is defined by thefirst cathode connection member disposed between the first connectionmember and the second connection member.
 6. A method for producing acapacitor stack, comprising: stacking a first electrode onto a firstelement, the first electrode having a first connection member having afirst proximal portion and a first foldable portion; folding the firstfoldable portion onto the first proximal portion such that the firstfoldable portion and the first proximal portion have a first thicknessapproximately equal to a thickness of the first element; stacking thefirst element onto a second element having at least one second electrodeand a second connection member; aligning the first connection member andthe second connection member to define a connection surface forconnection of the first electrode and the at least one second electrode;connecting the first electrode and the at least one second electrode atthe connection surface; disposing the stacked first element and secondelement in a case; and filling the case with an electrolyte.
 7. Themethod of claim 6, further comprising: applying a mask to the firstelectrode and defining a masked area, the masked area including at leastthe first connection member; etching the electrode, the mask resistingthe etchant; and removing the mask.
 8. The method of claim 7, furthercomprising applying the mask to two sides of the first electrode.
 9. Themethod of claim 7, further comprising cutting the first electrode from asheet.
 10. An apparatus for patient therapy, comprising: a flatcapacitor stack having at least a first separator disposed in alignmentbetween a first substantially planar electrode and a secondsubstantially planar electrode, the first substantially planar electrodehaving a first connection member with a first proximal portion and afirst foldable portion, the first foldable portion folded onto andabutting the first proximal portion, the abutting first proximal portionand first foldable portion having a first thickness approximately equalto the first element thickness; and a third substantially planarelectrode in stacked alignment with the second substantially planarelectrode, the third substantially planar electrode having a secondconnection member, with the first connection member and the secondconnection member are in alignment defining a connection surface forconnection of the first substantially planar electrode and the thirdsubstantially planar electrode; a case having at least one feedthrough,the capacitor stack sealably disposed in the case; programmableelectronics connected to the capacitor; and a housing adapted forimplantation in the patient, the case and programmable electronicsdisposed in the housing, wherein the flat capacitor stack and the caseare adapted to deliver to the patient from about 5.3 joules per cubiccentimeter of capacitor stack volume to about 6.3 joules per cubiccentimeter of capacitor stack volume.
 11. The apparatus of claim 10,further comprising four layers organized serially in the order of asecond separator, a cathode, the first separator, and an anode havingthe first connection member; with the first separator, cathode, andsecond separator have a combined thickness approximately equal to thethickness of the anode.
 12. The apparatus of claim 10, furthercomprising: a first element having a plurality of layers organizedserially in the order of a first anode layer including the firstconnection member, the first separator layer, and a cathode layer havinga first cathode connection member; and a second element having aplurality of layers including a second separator and a second anodelayer including the second connection member; wherein the connectionsurface is defined by the cathode connection member disposed between thefirst connection member and the second connection member.
 13. Anelectrode stack, comprising: a first element having at least a firstsubstantially planar electrode and a second substantially planarelectrode in stacked alignment; a second element in stacked alignmentwith the first element, the second element having at least a thirdsubstantially planar electrode and a fourth substantially planarelectrode in stacked alignment; a first connection member of the firstelement, the first connection member including a first proximal portionand a first foldable portion, the first foldable portion folded onto andabutting the first proximal portion, the abutting first proximal portionand first foldable portion having a first thickness approximately equalto a thickness of the first element; and a second connection means forinterconnecting the second substantially planar electrode and the forthsubstantially planar electrode, wherein the first substantially planarelectrode and the third substantially electrode are interconnected, andthe second substantially planar electrode and the fourth substantiallyplanar electrode are interconnected, and the electrode stack is adaptedto deliver from about 7.0 Joules/cubic centimeter of electrode stackvolume, to about 8.5 Joules/cubic centimeter of electrode stack volume.14. The apparatus of claim 13, wherein the first connection memberincludes a brittle etched portion and an unetched means for bending. 15.The apparatus of claim 13, wherein the first connection means includesunetched means for welded interconnection of the first substantiallyplanar electrode and the third substantially planar electrode.